Motorists driving conventional vehicles on freeways typically use visual information on their surroundings, together with whatever traffic related information that might be available, to select driving lanes and target speeds. In partially automated vehicles, this information may be enhanced by sensors located on the vehicle. Fully automated vehicles primarily use vehicle based sensor information to collect nearby status information and employ interpretative algorithms to convert this information to lane and speed choices.
In recent years, the increase in traffic levels along with difficulties with the construction of new freeway facilities has resulted in strategies that manage lane use. These strategies include the preferential assignment of classes of vehicles to specific lanes and the use of aggressive tolling strategies. In some cases, these strategies are lane specific and may vary with time-of-day or with traffic conditions.
An additional set of strategies (that may also be traffic responsive or that may vary with time of day) termed “active traffic management” also limit and control the use of lanes. These strategies have been employed in Europe for some time (see Fuhs, C., Synthesis of Active Traffic Management Experiences in Europe and the United States, FHWA Report No. FHWA-HOP-10-031, May, 2010) and are being increasingly emphasized by intelligent transportation systems in the U.S. Table 1 shows the strategies that constitute this set.
TABLE 1Active Traffic Management StrategiesSpeedUtilizing regularly spaced, over lane speed and lane control signs toHarmonization/dynamically and automatically reducing speed limits in areas of congestion,Lane Controlconstruction work zones, accidents, or special events to maintain traffic flowand reduce the risk of collisions due to speed differentials at the end of thequeue and throughout the congested area.Queue WarningUtilizing either side mount or over lane signs to warn motorists ofdownstream queues and direct through-traffic to alternate lanes - effectivelyutilizing available roadway capacity and reducing the likelihood of collisionsrelated to queuing.Hard ShoulderUsing the roadway shoulder (inside or outside) as a travel lane duringRunningcongested periods to alleviate recurrent (bottleneck) congestion for all or asubset of users such as transit buses. Hard shoulder running can also be usedto manage traffic and congestion immediately after an incident.JunctionUsing lane use control, variable traffic signs, and dynamic pavementControlmarkings to direct traffic to specific lanes (mainline or ramp) within aninterchange area based on varying traffic demand, to effectively utilizeavailable roadway capacity to reduce congestion.DynamicChanging major destination signing to account for downstream trafficRe-routingconditions within a roadway network or system.LaneImproving or facilitating traffic flow in response to changing roadwayManagementconditions. Lane management includes controlling use of lanes by vehicle(or Managedeligibility (carpool or transit), access control, and price.Lane)Variable Speed Dynamically changing speed limit signs to adjust to changing roadwayLimitsconditions, oftentimes weather related.Shoulder UseUse of the shoulder by time of day for transit or HOV, and in some instancesgeneral purpose traffic, to provide improved mobility along or withincongested corridors.Pricing-basedManaging traffic demand and flow using priced lane facilities, where trafficManagementflow in the priced lane(s) is continuously monitored and electronic tolls arevaried based on real-time or near-real-time demand. Pricing of roadwayfacilities can collect a toll from all users of the facility. In the case of highoccupancy toll (HOT) lanes, transit and carpools with a designated numberof occupants are allowed to use the priced lanes for free or a reduced rate.
Motorists are traditionally informed about lane selection associated with these strategies by dynamic message signs (DMS) also called variable message signs (VMS), by lane control signals (LCS) and by changeable speed limit signs controlled from a transportation management center (TMC). The driver uses this information, together with preferences that he/she may have and constraints imposed by the vehicle that he/she is driving, to select the appropriate lane and speed.
There have recently been significant developments in the development of automated vehicles. Levels of automation have been classified as follows by two agencies as shown in Table 2.
TABLE 2Levels of AutomationUS - NationalGerman FederalHighway TrafficHighway ResearchSafetyAutomation FeaturesInstitute (BASt)Administration*Driver only.10Driver assistance - The driver controls either21longitudinal or lateral steering. The other task may beautomated to a certain extent.Partial Automation - The system takes over32longitudinal and lateral control. The driver monitorsthe system and shall be prepared to take over control atany time.High automation - The driver must no longer43permanently monitor the system. In the event of a take-over request, the driver must take over control with acertain time buffer.Full automation - In the case of a take-over request that54is not followed, the system returns to the minimal riskcondition.*Lutin, J. M, Kornhauser, A. L., and E. Lerner-Lam, “The Revolutionary Development of Self-Driving Vehicles and Implications for the Transportation Engineering Profession” ITE Journal,Vol. 83 No. 7, July, 2013.
The following discussion employs the U.S. classification system.
Automated vehicles at levels 2 through 4 generally provide two capabilities:                Navigation—The sequence of roadways to be utilized and turning directions to implement this sequence. These directions are recalculated so that failure to follow them will result in a new planned path.        Longitudinal and lateral control of the vehicle.        
With the rapid improvement in implementing technology at Levels 2-4, the emphasis being placed on its implementation by auto manufacturers and others, the adoption of some form of authorization by three states (see Kelly, R. and M. Johnson, Legal Brief, Thinking Highways, North American Edition, October, 2012), it has been estimated that significant operational use may be achieved in ten to twelve years (see Self-Driving Cars: The Next Revolution, KPMG and the Center for Automotive Research).
At Levels 0 and 1, the functions of lane and speed selection are adequately performed by the driver. Research (Redelmeier, D. A. and R. J. Tibshirani, Are Those Other Drivers Really Going Faster?, Chance, Vol. 13, NO. 3, 2000) has shown, however, that drivers often incorrectly perceive that adjacent lanes are moving faster and are thus motivated to change lanes unproductively. This results in needless fuel consumption and a crash rate that is higher than otherwise would be the case. Guidance to the motorist on when a lane change would be appropriate will contribute to a smoother, safer ride with reduced fuel consumption. The Automated Lane Management Assist (“ALMA”) concept disclosed in the present application provides this capability.
As the intent of levels 2 to 4 is to reduce, and ultimately eliminate the driver's real time participation in vehicle operation and management, a scheme to coordinate these decisions with the current limited access highway lane use and speed limit requirements as well as with the characteristics of the vehicle and the general preferences of the driver is required.